Patent application title: Fixed Swirl Inducing Blast Liner

Abstract:

Wear is reduced in abrasive slurry service at an outlet into an annular
space defined by the wellbore and around the tool. In a gravel packing
application with a crossover, the slurry exits a central passage and goes
into an internal annulus in the tool. Turning vanes that make at least
one full turn and that have a height at least partially the height of the
annular space are there to impart a swirl movement to at least a portion
of the slurry stream. The swirling motion has beneficial effects of
reducing turbulence which allows a velocity reduction for a comparable
output volume. As a result of the lower turbulence leading to the final
exit from the tool into the surrounding annulus, the exit ports
experience reduced erosion and longer service life.

Claims:

1. An erosion reduction apparatus for a flow path in a downhole tool,
comprising:a body having a passage therein;a plurality of stationary
projections extending at least in part into said passage to change the
direction of flow in said passage.

11. The apparatus of claim 6, wherein:said projections define a bypass
portion of the passage where flow is not directly affected by said
projections because of their height.

12. The apparatus of claim 1, wherein:said projections comprise a square
or rectangular shape in cross-section.

13. The apparatus of claim 1, wherein:said body is a part of a crossover
tool assembly further comprising a screen mounted below said body and
said passage is within said crossover tool leading to an outlet above
said screen.

14. The apparatus of claim 13, wherein:said body further comprises an
inlet to said passage with said projections disposed between said inlet
and said outlet.

18. The apparatus of claim 17, wherein:said projections extend only
partially across said passage in a direction perpendicular to flow.

19. The apparatus of claim 18, wherein:said projections reducing erosion
downstream from a slurry that flows through said passage.

20. The apparatus of claim 19, wherein:said projections reduce turbulence
of flow through said passage.

Description:

FIELD OF THE INVENTION

[0001]The field of the inventions is slurry delivery devices for downhole
use and more particularly features of such devices that resist wear and
erosion at the delivery ports.

BACKGROUND OF THE INVENTION

[0002]Gravel packing and fracturing equipment involves moving a slurry
flow from an internal flow bore through an internal annulus in the tool
and ultimately out an exterior wall to an outer annulus usually around
screens. Typically the tool that is used is a crossover that can take
various positions for delivery of fracturing fluid and at another time
delivery of gravel slurry with other positions that allow removal of
excess fluid through circulation or reverse circulation.

[0003]The gravel slurry is fairly abrasive and when combined with the flow
rates that can occur in the crossover tool it often results in high wear
of parts that receive an impact from the fluid stream as it changes
direction within the tool. One effort to address the erosion issue within
the tool is to provide a sleeve after the first turn from a central flow
path to an internal annulus. In U.S. Pat. No. 7,096,946 such a sleeve 80
is rotatably mounted to turn on its longitudinal axis and the flowing
slurry stream interacts with internal vanes 66. The objective here was to
extend the wear of sleeve 80 by rotating it so that the slurry impinged
on a full circumference on the inside wall of sleeve 80 rather than a
fixed spot.

[0004]Other efforts to protect slurry outlet ports have focused on
aperture liners that are slightly smaller than the aperture itself. These
liners could be in the form of a sacrificial sleeve or inserts as for
example illustrated in U.S. Pat. No. 5,636,691. Crossover tool assemblies
in general are illustrated in U.S. Pat. No. 6,923,260. Vanes outside of
sand screens assemblies for evenly distributing gravel after release from
the crossover is shown in U.S. Pat. No. 4,995,456.

[0005]Spiral vanes have been used downhole in separator service such as
illustrated in item 304 in U.S. Pat. No. 7,174,959 and item 20d in U.S.
Pat. No. 4,273,509. Spiral vanes 112 in U.S. Pat. No. 4,132,075 are used
to promote mixing to improve heat transfer in a geothermal application
where turbulence is sought as an improvement to heat transfer rates.
Spiral vanes can be combined with a centralizer to promote distribution
of pumped cement for an annular space around a tubular as disclosed in
U.S. Pat. No. 5,097,905.

[0006]To address an erosion problem with slurry outlet ports in downhole
equipment and more particularly in crossover tool systems that deliver
fracturing fluids and gravel slurries, the present invention proposes a
technique to improve flow dispersion and reduce turbulence in the tool so
as to decrease the exit velocity of slurry from ports to a lower rate and
consequently reduce the erosion effect. The result is accomplished by
inducing a swirl in at least a portion of the flowing stream with the
beneficial result being that void spaces in an internal tool annulus are
minimized which results in an effective increase in flow area which in
turn leads to less turbulence, better filling of the annular volume with
a resulting reduction in velocity and longer useful life for the ultimate
exit ports into a surrounding annulus such as around gravel pack screens.
These and other advantages of the present invention will be more readily
apparent to those skilled in the art from a review of the description of
the preferred embodiment and associated drawings while recognizing that
it is the claims that determine the full scope of the invention.

SUMMARY OF THE INVENTION

[0007]Wear is reduced in abrasive slurry service at an outlet into an
annular space defined by the wellbore and around the tool. In a gravel
packing application with a crossover, the slurry exits a central passage
and goes into an internal annulus in the tool. Turning vanes that make at
least one half turn and that have a height at least partially the height
of the annular space are there to impart a swirl movement to at least a
portion of the slurry stream. The swirling motion has beneficial effects
of reducing turbulence which allows a velocity reduction for a comparable
output volume. As a result of the lower turbulence leading to the final
exit from the tool into the surrounding annulus, the exit ports
experience reduced erosion and longer service life.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a section view of a gravel packing assembly showing the
flow of slurry through it;

[0009]FIG. 2 shows a part of FIG. 1 in greater detail focusing in on the
swirling action in the section with vanes;

[0010]FIG. 3 is a perspective view of the vanes that impart the swirling
action to the slurry flow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011]FIG. 1 shows casing 10 and a gravel packing assembly 12 located
within. An external packer 14 is set against the casing 10. A crossover
tool 16 is shown in a position for gravel deposition in annulus 18 around
screens 20. A ball 22 has been dropped to a seated position blocking off
passage 24. Arrow 26 represents slurry being pumped from the surface
through passage 24. The flow exits through openings 28 into an inner
annulus 30. Arrow 32 represents this flow. In annulus 30 vanes 34, best
seen in detail in FIG. 3, impart a swirling motion to the slurry flow in
annulus 30. The flow of slurry then exits ports 36 into annulus 18 as
illustrated by arrow 38. The solids from the slurry remain in annulus 18
while the carrier fluid goes through screen 20 as represented by arrow
40. Flow continues as represented by arrows 42 and 44 to bypassing ball
22 to exit into annulus 46 above the packer 14 as indicated by arrow 48.

[0012]Focusing now on what happens between ports 28 and 36 in annular
space 30 as shown in more detail in FIGS. 2 and 3 the exiting flow from
ports 28 has a spin imparted to at least a portion of the annular flow by
the vanes referred to generally as 34. FIG. 3 shows two spirals 50 and 52
that are circumferentially 180 degrees apart. However, additional spirals
can be used that are uniformly or differently spaced circumferentially.
The spirals can track parallel to each other and the number of turns is
preferred to be at least 180 degrees of revolution along the path of a
single spiral. If the pitch of the spirals is the same what is created
are flow paths of constant width as represented by the constant spacing
between the spirals. The shape of a given spiral in cross-section can be
square, rectangular, trapezoidal or a rounded shape such as semicircular
or a partially elliptical shape. The height 54 that a spiral such as 50
extends into the annulus around which it circles can comprise the entire
height of the annulus in which case all the incoming slurry flow will be
subjected to a spin created by the spirals or the height can be shorter
than the height of the annulus 30 in which case some of the flowing
slurry steam will have a spin imparted to it while some passes the
spirals without directly having a spin imparted to it. It depends on how
much pressure drop is acceptable based on the capacity of the surface
equipment delivering the slurry and returning the screened carrier fluid
to the surface.

[0013]The benefit of using vanes such as 50 and 52 is that the flow
characteristics are changed to a more dispersed and ultimately less
turbulent flow which tends to eliminate or reduce voids and reduce the
pressure required to circulate the slurry out through openings 36. The
benefit comes as a velocity reduction of the slurry making an exit at
ports 36 due to effectively increasing the flow area by dispersing the
flow throughout the annulus. The result being less erosion that can limit
the service life of the gravel packing equipment shown in FIG. 1.

[0014]This benefit is to be distinguished from the design in U.S. Pat. No.
7,096,946. There the vanes were very short along the spiral path because
the sole purpose of the vanes was to impart a spin to the tube 80 so that
the exiting slurry didn't hit the same spot constantly when emerging from
a central flow passage. There was no consideration given to the erosion
that could occur at the outlet below the spinning sleeve. The short
length along a spiral path was such that no significant benefit from a
turbulence or velocity reduction near the ultimate exit from the gravel
pack assembly was envisioned or obtained.

[0015]While the vanes such as 50 and 52 are illustrated in slurry service
they can also be adapted for use in high velocity fluid applications in
liquid or gas service such as steam such as in injection applications in
oil sands service. While the preferred embodiment is an application in an
annular space, the vanes can also be used in flow lines or pipelines to
reduce turbulence and increase throughput or required pumping power. The
vanes such as 50 and 52 can be made of a hardened material or be
externally coated with a hardened material to resist erosion from the
slurry flowing past. The vanes can be mounted on a replaceable sleeve for
rapid changing or they can be made integral to a wall that defines a
flowpath where they are mounted.

[0016]The above description is illustrative of the preferred embodiment
and many modifications may be made by those skilled in the art without
departing from the invention whose scope is to be determined from the
literal and equivalent scope of the claims below.